Hi! After 41 years of being on the tower it is time to upgrade the antenna. Has anyone made a modification of 40m 4el KLM - Big sticker and replaced linear loading rods with high Q coils? We are awar
After 41 years of being on the tower it is time to upgrade the antenna. Has anyone made a modification of 40m 4el KLM - Big sticker and replaced linear loading rods with high Q coils? We are aware of
Hello SimonK7QA and I have been playing with the exact thing you are contemplating, except that we are doing it on an old Hy-Gain DIS-72 linear loaded 40 meter beam. We started by winding loading coi
Rather than try to duplicate a design that is decades old, I think it would make more sense to redesign the antenna using loading coils. VE6WZ has some loading coil information on: https://www.qsl.ne
Greetings All, I was considering a similar approach, by taking the existing design and changing the linear loaded elements into center loaded dipoles. Start with coil placement at LL insulator and tu
The main motivation of changing to coils would seem to be the increased Q and decreased loss. But a non-obvious benefit is a broadening of the band width. Any linear loading scheme has the drawback t
After 41 years of being on the tower it is time to upgrade the antenna. Has anyone made a modification of 40m 4el KLM - Big sticker and replaced linear loading rods with high Q coils? We are aware of
Definitely true. There is some benefit, however, to use two loading coils on either side of center for each element (instead of center coils) because that gives better current distribution along the
Definitely true. There is some benefit, however, to use two loading coils on either side of center for each element (instead of center coils) because that gives better current distribution along the
On 4/28/2020 3:20 PM, David Gilbert wrote: There is some benefit, however, to use two loading coils on either side of center for each element (instead of center coils) because that gives better curre
I bought a used EF180C (F12) LL loaded 86' rotary 80m dipole, tossed the LL wires, coils, and relays, modeled it with YagiMech (DXEng) and upgraded it mechanically for 90mph (was maybe 65mph). The LL
I just tried a quick model to see if a single loading coil at the center of a 40m dipole element was feasible. For simplicity I modeled a 46-foot element with constant 0.75" diameter. I compared two
On 4/28/20 4:18 PM, Jim Brown wrote: On 4/28/2020 3:20 PM, David Gilbert wrote: There is some benefit, however, to use two loading coils on either side of center for each element (instead of center c
Stretching out the current improves the field pattern ... i.e., "gain." I'm not talking resistive effects. That's why "extended" dipoles with series capacitors (which makes the length longer for th
Whether NEC accurately models the current isn't the point. You don't need a model to know that if you push the coil out away from the center the portion of the current between the coil and the cente
Can you elaborate on this? John KK9A <snip> Any linear loading scheme has the drawback that the effective loading inductance is directly proportional to frequency; exactly what you don't want. Rick N
This was a very interesting single loading coil discussion with surprising data. Kudos to Jim W6RMK and Brian K6STI! Also the coil sensitivity to moisture is alarming to those of us with OptiBeam and
Yeah, I was expecting the two-coil design to have better VSWR bandwidth. Did you compare the radiation resistance of the two designs? I would expect the one coil design to have a lower radiation resi
The inductance of a linear loading wire goes up as the frequency increases. It acts similarly to a transmission line. You typically would like the inductance to go down (with increasing frequency),
Whether NEC accurately models the current isn't the point. You don't need a model to know that if you push the coil out away from the center the portion of the current between the coil and the cente